Steering You Straight - Heim-Joints vs. Tie-Rod Ends

Steering is one of the most important components of your 4x4. If you toast a transmission or break an axle you can still steer to the side of the road. Lose your steering and you are just along for the ride. Factory steering is good for a stock vehicle, but when you start swapping axles or adding bigger tires you need something better. Better materials and increased wall thickness are common upgrades for tie rods and drag links, but oftentimes not enough thought is given to the end of those steering links.

Some sort of joint is required to accommodate movement, both from the tires turning left and right and the suspension cycling up and down. On a solid axle the tie rod doesn’t have a wide range of motion, regardless of whether it is mounted to the middle of the steering knuckle or above it. By contrast, the drag link used in crossover steering (where the drag link goes from the steering box to the passenger-side knuckle) must travel through the full range of suspension travel without binding. Tie-rod ends and Heim joints are the two choices for your steering. Which is best for your application depends on a number of factors.

A Case for Tie-Rod Ends
All factory steering linkages come with tie-rod ends that are tapered and fastened with castle nuts and cotter pins. The tapered joint mates with the corresponding knuckle or steering arm, retaining a tight connection. The castle nuts with cotter pins add another layer of safety and minimize maintenance. Grease zerks in the top of the tie-rod end allow them to be lubricated for long life, and rubber boots over the end of the joint retain the grease and keep out mud, water, and dust.

Not all tie-rod ends are created equal. We have had the best luck with Moog parts. The added reliability is worth the small increase in price, and they are made in America. GM tie-rod ends (Moog PN ES2233L and ES2234R) are popular not only with Chevy owners but Jeeps, Toyotas, and buggies too, thanks to their large 7⁄8-inch threaded shanks and common availability. They are often referred to as “one ton” tie-rod ends, but they actually came on ’76-’911⁄2- and 3⁄4-ton trucks. True “one ton” tie-rod ends use 1-inch threaded shanks but are not as common or easy to source.

A Case for Heim Joints
While tie-rod ends have several great qualities, they are not perfect for every situation. Heim joints are commonly used for steering on buggies and race trucks because they can be found in much larger sizes than even “one ton” tie-rod ends. While we are using the term Heim joint, named after the inventor Lewis Heim, these are also known as spherical rod ends. In addition to steering, they are commonly used in suspension links, throttle linkages, and other components that need to pivot and be adjustable in length. Weld-in bungs and taps for Heim joints are much less expensive and easier to source than the 7⁄8-inch, 18-threads-per-inch tie-rod ends, but the Heim joints themselves and related hardware can often add up to make the overall cost greater than tie-rod ends.

Mounting steering links in double shear will reduce the leverage on the fasteners and greatly increase the strength of the steering system. This should be done whenever possible when using Heim joints.

While tie-rod ends have a taper, Heim joints are attached to steering linkages with straight bolts. The leverage exerted on the Heim joint can cause the bolt to wobble and loosen. The best way to combat this is to mount the Heim joint in double shear, where it is captured above and below. Also use the highest-quality fasteners you can find, as they are subjected to enormous loads.

If your state has yearly vehicle inspections, Heim joints might not pass. Check your local laws to see if this is an issue before shelling out any money on new steering components.

By using a safety washer, a Heim joint can be mounted in single shear and yet effectively captured top and bottom should the ball separate from the housing. Some misalignment spacers provide this same level of safety, but the safest option is still to mount the Heims in double shear.

Like tie-rod ends, all Heim joints are not created equal. We have had good success with QA1 and FK rod ends, and even within those brands there is a wide spectrum of features and prices. Teflon-lined alloy Heim joints are much better for steering than budget steel Heim joints intended for tractors because of their tighter tolerances, which seals out contamination. Plus, Teflon has the ability to lubricate the joint and keep it operating smoothly and quietly.

The Final Word
Regardless of what ends you choose for your steering linkages, pick the highest-quality components you can afford and check them regularly. Both typically use jam nuts to connect them to the tie rod or drag link, and the jam nuts should be checked regularly to ensure that they are tight. For tie-rod ends, maintenance involves greasing the joints and making sure there are no tears in the boots. Heim joints must remain clean and tight, with fasteners torqued to specification. Penetrating oil can be added to quiet down squeaks, but it also attracts dirt. Our research concluded that if you want to do the least amount of maintenance, stick with tie-rod ends. If you want maximum strength and parts that are easy to swap on the trail, quality Teflon-lined Heim joints might be a better choice for you.

Righty Tighty Lefty Loosey
Whether you use tie-rod ends or Heim joints, most tie rods and drag links use left-hand threads on one side and standard right-hand threads on the other side. Doing so allows you to adjust the length of the steering links without removing them from the vehicle. There are some benefits to using just right-hand threads. One advantage is having to carry less unique spare parts. There’s also no need to purchase a left-hand tap. You would have less concern about the drag link or tie rod coming off if the jam nuts come loose because as one end threads out, it will be resisted by the other end, which is trying to thread in to the steering link. Weigh the pros and cons when building your next steering setup and decide what is most important to you.